Were the floods of November 1995 and February 1996 made dramatically worse by clear cutting and development?
It is extremely difficult to quantify the increase in flooding attributable to clear cutting and development. Most of the severe flooding in Western Washington occurs near the mouth of rivers having drainage areas of hundreds of square miles. Most of the runoff is the result of intense precipitation in the mountainous areas that are essentially undeveloped. Clear cutting is a factor and clear cutting increased significantly in the 1970s and ’80s. The effect of clear cutting on runoff from a clear cut area diminishes over time as the ground cover and forest is reestablished. Also, as was stated earlier, proportionally the effect of clear cutting is greatest in small to medium size flood events. The preponderance of evidence is that the increase in flooding in most basins last year attributable to development and clear cutting was small.
